Study the information about the structure: preposition (in/for/about) + -ing.
1. If a preposition is followed by a verb, the verb ends in -ing.
Are you interested in working for us?
How about meeting for lunch tomorrow?
Mike must be fed up with studying.
2. Remember the use of these prepositions + -ing.
Before + -ing
After + -ing
By + -ing
Without + -ing
Before going out, she called Martin.
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She has many problems without having to worry about yours.